Connectors have been used in the communications industry since it was originally developed for voice traffic. Connectors have gone through a number of evolutions so that it can support current 10G/1G/100/10 Mbps Ethernet. This technology will continue to evolve to support emerging high-speed 40G and 100G, along with other communication protocols and electronic equipment requiring electromagnetic components. As communication systems have begun to aggregate more and more individual ports in one box (i.e. 48 port Ethernet switches or multi-port routers), printed circuit board space has become very valuable. The connector manufacturers took the next step in the connector evolution by attempting to integrate external magnetics into the connector in order to reduce the system footprint, in addition to adding printed circuit boards with passive components to match parasitics from the integrated circuits (ICs) and connectors. The magnetics are required for isolating the user from internal voltage surges, or the electronics from external high voltage shorts and surges. They also limit the EMI electro magnetic interference emissions seen emanating from the system that is essential in compliance to rules and regulations associated with electronic equipment.
In current solutions, hand wound magnetics are integrated into the connector housing by soldering down these hand wound components onto posts or pads provided in the back of the RJ-45. In single jack housings, eight of these individually wound magnetic units needed to be attached to the proper connections and then squeezed into the back of the housing. Shown in FIGS. 1(a)-(b) are prior art components 100, where FIG. 1(a) shows hand-wound wires 102 wrapped around an annulus-shaped or toroid magnet 104, forming a magnetic unit 106, and FIG. 1(b) shows conventional connectors 108 and the difficulty in accomplishing this integration. Once all the magnetic units 106 are inserted they are covered with a gel material to hold them in place. This is time consuming and offers poor repeatability and performance since the magnetic units 106 are in close proximity and their spacing is difficult to control. Some efforts have been made to delineate the position of these units using guideposts or grooves in the housing but these have fallen into disuse due to cost and manufacturing cycle times. Controlling leakage and balancing primary and secondary turns across center tap is virtually impossible with these hand wound parts. Furthermore for higher frequency application it is not possible to control impedance and achieve wideband performance. Finally these components cannot be used to create subsystems and modules because of the inherent variations from hand winding.
In other assemblies, a horizontal donor PCB board can be inserted into the housing, which allows the manufacturer to place passives and the magnetics on the PCB where it again will be restrained with potting material. While this offers an improvement over other attempts it still offers limited performance since the magnetics are still hand wound and then placed, which limits performance and increases manufacturing cost. These boards also provide one other function, which is to provide a base for the connector.
OEM's (original equipment manufacturers) are now beginning to look at how to get to the next level of integration in their equipment. They would like to move to 96 port face plates on their boxes which means that the connectors and PCB space must get much more compact. Connectors (not RJ45 connectors) must get narrower and not go as deep as current designs offer. The current hand wound magnetic solutions do not satisfy this need due to mechanical constraints and hand assembly.
Currently transformer magnetics are hand wound, then epoxy-glopped and packaged. They are typically Quad Flat No leads (QFN), Gull wing or Ball Grid Array (BGA) packages. These hand wound components are used in non-Ethernet applications such as set top boxes, RF routers, RF mobile, internet and consumer electronics. When these hand wound transformers are integrated into a connector they may go onto a PCB substrate and be mounted in horizontal or vertical configurations. These are hand wound and hand soldered, attached to a thin printed circuit board and then attached inside of the connector. Critical parasitic parameters cannot be controlled such as leakage inductances and capacitive coupling this causes poor performance.
Accordingly, there is a need to develop low-cost, embedded planar magnetic components that are integrated into narrow and shallow communication connectors. There is a further need for an efficient and low-cost method of manufacturing such devices that eliminates damage to the ferrite material and reduces EMI, maximize the winding turns and controlling the winding parasitic inductance.